Fin device, in particular for water sports, and method of manufacture of such a device

ABSTRACT

A flipper device (1) is comprised of a fin forming front part (2) made of a relatively rigid material and device (F) for fixing the fin (2) to the foot (3) of the user. The fin (2), in its rear region (6) is fixed under the sole (4) of a foot piece (5) made of a material which is more flexible than that of the fin; at least the front part (11) of the foot piece is covered by a coating (10) of material which is more rigid than that of the foot piece (5). The coating (10) is integral with the fin (2) and is appropriate to transmit correctly an impulse from the foot (3) to the fin (2).

This application is a 371 of PCT/FR93/00383 Apr. 19, 1993.

FIELD OF THE INVENTION

The invention relates to a fin device, of the type comprising a frontpart forming a blade, made of a relatively rigid material, and means offastening the blade to the foot of the user.

The invention more particularly relates to such a fin device intendedfor the practice of the water sport known by the name "body-boarding",or the practice of diving, or of "aerobics" in water.

BACKGROUND OF THE INVENTION

The sport known by the name of "body-boarding" consists in trying tomove on the crest or close to the crest of a wave, while remainingface-down on a board whose dimensions are generally less than those ofboards used for surfing, which is performed standing on the board.

When waiting for a wave, a sportsperson who is "body-boarding" adopts aposition which is favourable for him/her to be carried along by thecrest of the wave. When the crest arrives, it is furthermore necessaryfor him/her to exert sufficient energy to gain a speed, in the samedirection as the crest, which allows the phenomenon of being carriedalong by the wave. For this purpose, the sportsperson is generallyequipped with fins which allow him/her to impart sufficient change inmomentum when the crest of the wave arrives. For these operations, thefin must remain substantially at the surface of the water andfurthermore contribute to steering the sportsperson and his/her board.

This explanation demonstrates why the fin must be made of a materialwhich is sufficiently hard to allow it to strike the water efficientlyand obtain the desired momentum.

It is also apparent that abrupt movements are involved and that it isimportant for the fin to be fastened reliably to the foot of the user.

In the case of fins intended for diving, the forces transmitted to thefin are less intense, but it is still necessary for the fin to berelatively hard in order to retain a good degree of efficiency;similarly for aerobics in water, it is necessary to exert a force whichwill cause energy to be expended.

When engaging in the water sports mentioned hereinabove, thesportsperson is moreover frequently called upon to walk wearing fins onhis/her feet between two sporting sessions. This results in sand, orother foreign bodies, being capable of entering the fins during such awalk, which is irritating.

SUMMARY OF THE INVENTION

The object of the invention is above all to provide a fin device, of thetype previously defined, which no longer, or to a lesser degree,exhibits the drawbacks mentioned hereinabove.

It is desired, in particular, for the fin device, whilst ensuringtransmission, under satisfactory conditions, of momentum from the footof the user to the blade, to exhibit a high degree of reliability asregards fastening the fin to the foot of the user, and to prevent theintroduction of irritating bodies, such as grains of sand, or the like,between the fastening means and the foot of the user.

According to the invention, a fin device of the type defined previouslyis characterized in that the blade is fixed in its rear region under thesole of a shoe element made of a material more flexible than that of theblade and in that at least the front part of the shoe element isprovided with a covering made of a material which is more rigid thanthat of the shoe element, this covering being solidly attached to theblade and being capable of correctly transmitting momentum from the footto the blade.

With such a device, the efficiency of the fin is retained by virtue ofgood transmission of momentum from the foot to the blade, and this finis more comfortable to use because introduction of irritating bodies,such as grains of sand, is reduced or eliminated by virtue of the shoeelement which, by virtue of its flexibility, is comfortable to wear.

Preferably, the covering of the shoe element, made of a more rigidmaterial, extends under the entire sole of this shoe element and rises,towards the rear part, to surround the heel region. The blade extendsunder a part of the sole, just as far as the front end of the heel, orunder the entire sole. The connection between the shoe element and theblade is thus particularly resistant to tearing.

Preferably, the blade includes at least one hole in the part intended tobe located under the sole, in particular for allowing injection of thecovering or of an adhesive.

Advantageously, the shoe element, of the slip-on boot or bootee type,includes an upright part which surrounds the ankle of the foot of theuser, this part including, towards the top, a tightening belt connectedto the element by at least two loops and allowing the entire peripheryof the top part of the shoe element to be tightened around the leg ofthe user; in the case of an ankle-length slip-on boot made of neoprene,a band of hooked fabric of the "velcro" type surrounds the foot at itsinstep part and passes through the sole; this fastening prevents the finslip-on boot from being lost and gives better support to the foot. Suchtightening makes it possible to prevent the introduction of foreignbodies, such as grains of sand, into the shoe, and maintains attachmentof the shoe element and of the fin to the leg of the user, even in theevent that the shoe element has become detached from the foot of theuser.

Advantageously, the shoe element is made of neoprene or of a materialhaving equivalent mechanical characteristics, while the covering whichjoins the shoe element to the blade is made of thermoplastic rubber orany thermoplastic material whose density is less than 1, for buoyancy ofthis fin/shoe assembly, which is made unsinkable.

The tightened belt is advantageously made of a band of fabric fittedwith complementary hooks, in particular the one known by the name"velcro". The blade is advantageously equipped, on each side, withlateral ridges whose mid-plane is substantially orthogonal to the planeof the blade; the blade may include a longitudinal central rib, oflesser height than the ridges. The ridges and the rib projectessentially upwards. These ridges and the rib allow the fin to have adirectional action.

The hardness of the blade may vary depending on the use of the fin/shoe;the same is true for the connecting material between the shoe elementand the fin.

The invention also relates to a method of manufacture of such a findevice by injection in two steps or in a single step, depending on theheight of the ridges of the fins.

In the case in which the ridges are of lesser height, allowing easydemoulding, the blade and the connecting covering are made by injectinga thermoplastic in a single step into a mould containing a former onwhich the shoe element has been placed.

In the case in which the ridges of the fins are relatively high, theprocedure is in two steps: in a first step, the blade is manufactured,by injection, from a relatively rigid material, while making at leastone hole in the part of this blade intended to be located under the soleof the shoe element; in a second step, the shoe element is placed on aformer arranged in mould halves, the whole being such that:

a free space is left between the internal surface of the cavity of themould halves and the shoe element engaged on the former, in the regionintended to receive the covering,

and each half of the mould has an opening, under the sole of the shoeelement, which is intended to be closed by a block facing a rear regionof the blade,

and the blade is next fitted on the block via its rear region, the blockincluding a duct which is aligned with a hole in the blade for injectingthe covering material,

then, after having closed the mould, the said covering is injected andspreads into the space lying between the former, the half of the mouldand a region of the blade, and establishes connection between the bladeand the shoe element.

Advantageously, the covering extends under the entire sole of the shoeelement and rises at the heel, this covering joining the rear part ofthe blade continuously.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention consists, apart from the arrangements describedhereinabove, of a certain number of other arrangements which will bedealt with in more detail hereinbelow with reference to one embodimentdescribed with reference to the attached drawings, but which is no waylimiting.

FIG. 1 of these drawings is a vertical section along the line I--I inFIG. 2 of a fin device according to the invention.

FIG. 2 is a plan view of the fin device in FIG. 1.

FIG. 3 is a diagrammatic view in vertical section of a mould, in theopen position, including an internal former for moulding the fin deviceaccording to the invention.

Finally, FIG. 4 is a horizontal section of the closed mould, afterinjection of the covering.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, in particular to FIGS. 1 and 2, a fin devicei can be seen which comprises a front part 2 forming a blade, made of arelatively hard and rigid plastic, in particular thermoplastic rubberwith suitable fillers for giving it the desired hardness. The hardnessof the blade 2 may be of the order of 85 Shore A, and generally liesbetween 5 and 90 Shore A.

Fastening means F are provided for holding the blade 2 on the foot 3 ofthe user.

The blade 2 is fixed under the sole 4 of a shoe element 5 of the shoe orslip-on boot type, this shoe element forming part of the fastening meansF. The blade 2 extends backwards, under the sole 4, by a part 6 whichstops in a region 7 represented by a vertical line in FIG. 1, locatedslightly in front of the heel of the foot 3. In a variant, the blade 2extends under the entire sole, rising at the heel.

The shoe element 5 is made of a flexible material, for example ofneoprene or of a plastic having similar mechanical characteristics,which is extensible and highly comfortable, making wearing of the finpleasant and efficient. The shoe element 5 rises above the ankle 8 ofthe user to a level 9. In a variant, the shoe element stops below theankle and is then held to the foot firmly using a band of hooked fabricof the "velcro" type, which passes over the instep and into the sole.

The shoe element 5 is connected to the blade 2 by a covering 10 made ofa material which is more rigid than that of the shoe element 5. Thematerial of the covering 10 advantageously consists of thermoplasticrubber whose density is less than 1.

The covering 10 covers at least the front part 11 (see FIG. 2) of theshoe element 5, that is to say the part covering the toes of the foot ofthe user. The covering 10 is connected to the blade 2. The contour ofthe front part of the covering 10 descends along lines 12 on either sideof the shoe, as shown by FIG. 1, so as not to trap the foot of the usertoo strongly and to retain the comfort created by the flexible materialof the shoe element 5. The covering 10 advantageously extends under theentire sole 4, as shown by FIG. 1, and rises backwards along lines 13 oneither side of the shoe element so as to enclose the lower part of theheel of the shoe element 5 in a turn-up 14.

The part 6 of the blade 2 is to some degree embedded in the covering 10whose thickness, as shown by FIG. 1, is larger behind the boundary 7 inorder to compensate for the absence of the part 6 of the blade, or mayalso be thinner if the part 2 of the blade rises up to the heel.

This blade includes, on these two longitudinal edges, ridges 15, 16which project essentially upwards, substantially perpendicularly to themain plane of the blade 2. The ridges 15, 16 may extend slightly belowthe blade 2 by ribs such as 15a (FIG. 1) whose height decreases from thefront end towards the rear part of the blade, the lower edge of the rib15a connecting, at the rear, with the lower surface of the assembly.

Advantageously, a longitudinal central rib 17 is provided on the upperface of the blade 2, this rib having a height less than that of theridges 15, 16. The rear end of the rib 17 is embedded in the covering10. The ridges 15, 16 and the rib 17 give the fin directional qualities.In particular, a sportsperson who is equipped with such a fin device andwho is lying face-down on a board propelled by the crest of a wave cansteer by keeping the fins on the surface of the water, the ridges 15, 16and the rib 17 being immersed in the water. The blade 2 includes, in itspart 6 lying below the sole, substantially in the region located underthe arch of the foot 3, at least one hole 18 allowing, in particular,injection of the covering 10.

The shoe element 5 is equipped, in a region lying above the ankle 8,with a tightening belt 19, consisting in particular of a band of fabricfitted with conjugate hooks, such as the one known by the brand name"velcro". This belt 19 is engaged in at least two buckles 20, or loops,fixed, in particular by sewing, in the vicinity of the front and rearmiddle top ends of the shoe element 5. Tightening the belt 19 around theleg of the user makes it possible to close the shoe element 5 inpractically leaktight manner around the leg and establishes a mechanicalconnection between the leg and the shoe element.

With the fin device 1 of the invention, the sportsperson, whilebenefiting from the comfort of the flexible material of the shoe element5, can efficiently transmit momentum to the blade 2 by virtue of thecovering 10 which connects and covers the toe region which is mainlyinvolved in propulsion. This covering 10 furthermore constitutes aprotection.

An advantageous method of manufacture of the fin device of the inventionwill now be described with reference to FIGS. 3 and 4.

After having separately prepared, on the one hand, the blade 2 with itsrear part 6 and, on the other hand, the shoe element 5, the procedure isas follows.

Use is made of a mould 21 including two halves 22, 23 which arearticulated in order to be openable. A former 24 is connected by anarticulation to the upper half of the mould 22 so as to be capable ofbeing released from an impression 25 provided in this half 22 andcorresponding to the former 24. The end part 26 of the former 24 whichis away from the articulation of the two halves 22, 23 corresponds tothe average shape of a foot for a given size. The shoe element 5,generally made of neoprene, is slipped over this part 26. The former 24has a thinner intermediate region between this part 26 and the other,widened end 27.

The lower half 23 of the mould includes an impression 28 correspondingsubstantially to the impression 25 of the upper half. The whole is suchthat, when the half 22 is folded down onto the half 23, and the mould isclosed, the former 24 is housed in the volume defined by the impressions25, 28. The wall of these impressions defines, around the sole of theshoe element 5, a free space 29 intended to receive the covering 10which will be injected.

The space 29 is closed, on the side opposite the articulation, by thepart 6 (see FIG. 4) of the blade 2 which is applied against the openings22a, 23a of the front ends of the halves 22, 23, by an articulated block30 forming a part of the mould. The block 30 includes a channel 31arranged so as to be located in line with the hole 18 in the part 6 ofthe blade.

When the mould is closed, the various pieces occupy the positionsillustrated in FIG. 4.

The mould is then heated to the moulding temperature, for example of theorder of 200°, and the material of the covering 10, in particularthermoplastic rubber, is injected through the channel 31 so as to passthrough the orifice 18 and fill the space 29, thus establishingparticularly effective connection between the part 6 of the blade 2 andthe relevant regions of the shoe element 5. For demoulding, the mould isopened and the shoe element 5 is removed from the former 26.

It should be noted that thermoplastic rubber adheres particularly wellto neoprene. A covering 10 made of polyurethane would also give goodresults with a shoe element 5 made of neoprene.

In the case in which the ridges of the blade have sufficiently lowheight to allow normal demoulding, the injection can be carried out in asingle step; the covering 10 is then made of the same material as theblade 2 and forms a single piece with it. The shoe 5 is fitted on aformer similar to the former 24 in FIGS. 3 and 4. When closing themould, a space is defined which corresponds to the entire blade andcovering. Injecting plastic into the mould makes it possible to producethe blade and the covering for connection to the shoe 5 in a singleoperation.

I claim:
 1. Fin device comprising a frontal part forming a blade, madeof a relatively rigid material, and means for fastening the blade to afoot of a user, said blade being fixed in its rear region under a soleof a shoe element made of a material more flexible than that of theblade, said shoe element having a heel region and a front part providedwith a covering made of a material which is more rigid than that of theshoe element, said covering being solidly attached to the blade andbeing capable of correctly transmitting momentum from the foot to theblade, and said covering extending under the entire sole of the shoeelement and rising, towards a rear part to surround the heel region. 2.Device according to claim 1, wherein the blade extends under at leastpart of the sole.
 3. Device according to claim 2, wherein the bladeincludes at least one hole in a part intended to be located under thesole, said hole allowing injection of one of said covering and anadhesive.
 4. Device according to claim 1, wherein the shoe elementincludes an upright part which surrounds the ankle of the foot of theuser, said upright part including a tightening belt connected to theshoe element by at least two loops, said belt allowing the entireperiphery of the upright part of the shoe element to be tightened aroundthe leg of the user.
 5. Device according to claim 4, wherein the shoeelement is made of neoprene, while the covering which joins the shoeelement to the blade is made of a thermoplastic material whose densityis less than one, in order to make the fin unsinkable.
 6. Deviceaccording to claim 5, wherein the tightening belt is made of a band offabric fitted with complementary hooks.
 7. Device according to claim 1,wherein the blade includes two sides, each side having a lateral ridgewhose mid-plane is substantially orthogonal to the plane of the blade,said blade further including a longitudinal central rib of lesser heightthan the lateral ridges.
 8. Device according to claim 1, wherein thecovering which joins the shoe element to the fin has a hardness lessthan or equal to that of the blade.
 9. Method of manufacture of a findevice comprising a front part forming a blade, made of a relativelyrigid material, and means for fastening the blade to a foot of a user,said blade being fixed in its rear region under a sole of a shoe elementmade of a material more flexible than that of the blade, said shoeelement having a front part provided with a covering made of a materialwhich is more rigid than that of the shoe element, said covering beingsolidly attached to the blade and being capable of correctlytransmitting momentum from the foot to the blade, said methodcomprising:manufacturing in a first step, from a relatively rigidmaterial, the blade by injection, while making at least one hole in apart of the said blade intended to be located under the sole of the shoeelement; placing in a second step, the shoe element on a former arrangedin mold halves which form a cavity, whereby a free space is left betweenthe internal surface of the cavity of the mold halves and the shoeelement engaged on the former, in a region intended to receive thecovering, and each half of the mold has an opening, under the sole ofthe shoe element, which is intended to be closed by a block facing arear region of the blade; fitting the blade on the block via its rearregion, said block including a duct aligned with a hole in the blade forinjecting the covering material, then, after having closed the mold,injecting said covering into the free space aligned between the former,the halves of the mold and a region of the blade, whereby the coveringspreads and establishes connection between the blade and the shoeelement.
 10. Method according to claim 9, wherein the covering extendsunder the entire sole of the shoe element and rises at the heel, saidcovering joining the rear part of the blade continuously.